Lycoming oil filter

[Rob Swain]

I've got a Lycoming O-320 in my RV6 which just has an oil screen, not a 'proper' filter.

I've nosed around for a filter conversion and there seem to be a selection of choices including Lycoming's own and various after market ones. Van's sell (and presumably recommend) the Casper Labs one that turns the filter 90 degrees and is around $250 but needs a $70 spacer as well.

Anybody got any recommendations?

[Sandy Hutton]

Rob, if Lycoming designed the engine to operate with an oil screen then that should be perfectly adequate. It's up to you if you want a bit of extra filtration but ask yourself if it's really necessary. When an engine starts to throw up the odd flake of metal, you're more likely to see it in the screen than by unravelling a yard of paper filter. Hands up who actually do this? Oh and then you have to arrange disposal of the element (landfill?)

[Steve Brown]

In adapting my O-200 to a full flow paper filter (with builting anti flow back valve and blocked filter bypass valve), I felt that a paper element would capture the smaller particles a coarse screen would let through. I've seen the embedded particles in the soft white metal main & big end bearings that make them look like an emery surface. No wonder the cranks need regrinding / replacing!
I got better oil pressure too.
Lycoming may have just stuck with the old screen due to the difficulties / expense of re certifying an engine.
Modern cars with their much tighter tolerances may go so much further between filter/oil changes partly because of better filtering. You don't see them with screens.
Makes filter changes a pleasure too!

[Rob Swain]

Rob, if Lycoming designed the engine to operate with an oil screen then that should be perfectly adequate.

Good point and I'd agree with that were it not for the fact that Lycoming produce their own oil filter conversion! Trouble with theirs (as I understand it) is that it sticks straight out the back and therefore fouls the firewall on a lot of installations, including the RV's. Oh yes, it's flippin' expensive too! For these reasons I was looking at the Casper Labs filter conversion as it clears the firewall and makes oil changes cleaner, easier and less frequent (50 hours between changes rather than 25 with a screen).

Just wanted to gauge opinion as to whether it's a good conversion or if another one gets more brownie points

I'm already a convert to filters having had a filter conversion on a C85. It has previously been observed that the Continental oil screen will stop the average house brick but very little else, although I do accept that I'm tarring Lycoming's screen with the same brush on this one.

[Dave Hall]

Actually, at least some of the water-cooled VW engines do have oil screens - they protect the oil pump being jammed by large items (not sure where they would come from), as I know to my cost. They are however, inaccessible for normal servicing within the sump.

I ran a big-end in a Polo (or rather, my son did) because a previous owner had allowed the oil to get old, or low or both, and the gauze around the oil pick-up in the sump was almost completely blocked with black deposits. Shame it hadn't got the old gauze oil screen like a Beetle that can be cleaned each oil change. Still, a new bearing, polishing in situ of the crank and for a £10 outlay it went on for another 50,000 miles and two more male students learning to drive, and was still running sweetly at 145,000 miles when finally other factors took over and it was scrapped.

[Alan George]

We have an RV4 with a Lycoming O-320, not much room between engine and firewall, and have fitted an oil filter with 90 degree adapter and spacer. It is easy to change the filter and all seems well-engineered. Unfortunately I do not have the paperwork at home but can find out the manufacturer when I go to the airfield.

[PB]

It's all about the oil. The simple version goes like this....

When the C85 was new Ashless Dispersant and other detergent oils had not been invented.

With 'straigh' oil any big lumps in the oil were stopped by the screen and the fine particles settled out into all the nooks and crannies inside the engine. The TBO was much shorter and all the accumulated sludge was cleared out each time the engine was serviced. Not ideal but it sort of worked.

Led mostly by the automotive market, the oils have become much more high-tech and most critically, most of them have detergents in them that help to keep the fine particles suspended in the oil rather than forming sludge. The aero engine version of this is your typical 'AD' oil. A decent filter is then required to remove the fine particles that are now swimming round the inside of the engine.

There's a bit more to it than that (lower viscocity and much tighter tollerances being the main thing on newer engines) but in simple terms, if you are running a modern oil a filter is probably a good thing. In any event a simple screen upstream of the oil pump keeps the big bits out and while it's clearly not ideal, a gear pump can pass quite big 'bits' before it seizes.

For similar reasons, in a well used engine (flight schools etc.) where acid build up and condensation is not a problem, with decent filtration, there is probably no technical reason why a good quality modern synthetic aero-engine oil could not go 200-300 hours or more between services. Your typical modern BMW or Ford is quite happy with an oil change every 15,000 or 20,000 miles after all. For sure an aero engine is working much nearer peak torque for much more of the time than a car engine but our 50-hour change is equivalent to about 2,500 miles in a car. It will never happen as the FAA, CAA and not least, the oil companies will never sanction it for obvious reasons.

[Rob Swain]

Alan,
Thanks for the piccie. That will be a great help when I pull the cowling off the RV6. Looks like the Casper Labs one that I was thinking of.

PB,
Thanks for the info.
You make a good point about acid and condensation so reaching 50 hours in 4 months for a single pilot aircraft makes the my extended oil change interval advantage a moot point. Good food for thought about the changes (ashless dispersants etc) in oils though.

Think I'll be going for an oil filter, and it's looking like the 90 degree offset one!

[mike newall]

Filter or not, unless you are doing 100 hours plus per year, you should be considering oil changes at 25 hours/4 months which ever comes first. 6 quarts at £4 a quart, less if bought in the States or through someone like Silmid is cheap maintainence.

Small Continentals are even worse - no filter, I would always do 10 hours between changes but then you are only changing 4 quarts usually.

[David Kean]

Alan, your picture appears to show a B&C adaptor, here..

http://www.bandc.biz/cgi-bin/ez-catalog ... ?20X358218

Rob, I have a spacer for one of these, need to check the size though.

David

[Phil Burgess]

Also, Dont forget that when installing a spin on filter, you have to leave room to be able to unscrew the filter right to the end of the thread before you can remove it. Don't just offer up the assembly where it will fit and go drilling. I fell foul to this one with my last aeroplane. Also if mounted in the position shown in the picture you will spill a considerable amount of oil down the back of the engine on removal. Best to get a remote filter instalation and install with the opening facing upwards. Try these for the filter end : http://www.speedflowshop.co.uk/mocal-re ... -148-c.asp

[David Kean]

To stop the oil spill simply put a plastic bag around it, from the bottom up, works a treat
Alternatively ( I am told but I haven't tried this ) poke a hole in the top with a small screwdriver and leave for 10mins.

[David Broom]

For similar reasons, in a well used engine (flight schools etc.) where acid build up and condensation is not a problem, with decent filtration, there is probably no technical reason why a good quality modern synthetic aero-engine oil could not go 200-300 hours or more between services. Your typical modern BMW or Ford is quite happy with an oil change every 15,000 or 20,000 miles after all. For sure an aero engine is working much nearer peak torque for much more of the time than a car engine but our 50-hour change is equivalent to about 2,500 miles in a car. It will never happen as the FAA, CAA and not least, the oil companies will never sanction it for obvious reasons.

I stand to be corrected but my understanding from Rob Midgley's ( Shell ) excellent presentations is that modern aero-oils are at best semi-synthetic. A natural oil content is necessary to mop up the by-products of burning a leaded fuel, something the synthetic components can't do. These by-products of leaded fuel use then reduce the lubrication effectiveness hence the more frequent oil changes than motor cars. It is primarily the use of unleaded fuel which has led to the long intervals between oil changes on cars, not the oil or materials technology.

[PB]

David

Absolutely correct regarding the semi-synthetic and lead in fuel. In my defence, I did head my piece "the simple version".

To expand a bit, (also a simple version) the lead in 100LL probably does more harm than good in a most low powered aero-engines and certainly so in all automotive derived ones. This too is a historical left-over, in this case from WWII when compression ratios were high and engine lives were short. Much of the early power increase from the original RR Merlin engine came about as much through the introduction of American 100/130 fuel and the higher compression ratios/boost pressure this allowed as it did from any fundamental design changes.

In combustion terms, anything with a compression ratio of 8:1 or less will run quite happily on standard unleaded, though there may be issues with seals, pipes etc. and in some cases valve seats.

There are however enough higher powered (mostly turbo) engines around in the fleet that do require a high octane fuel that the rest of us are stuck with the lead as it is simply uneconomic to refine, distribute and stock more than one grade of aviation fuel.

I would say that the reduced service intervals on modern cars are due to a combination of no lead in the fuel, better oil (especially synthetics) and improved metallurgy.

[Rob Swain]

As a matter of interest...

Just how much lead is in 100LL.

In the past Shell have indicated in one of their missives that it is about 8 times as much as old 2 star mogas used to have.

But the LL in 100LL stands for Low Lead.

If the 2 statements above are true, how much lead used to be in old 100 and 130 grades?